1. Field of the Invention
The invention relates to a galvanic cell comprising an outer metallic jar which on its outside has an insulating and decorative layer.
2. Description of the Related Arts
Galvanic cells which are mainly used in electrically operated appliances have an electrically insulated jacket and two contacts which, as a rule, are situated opposite one another. The electric circuit of the electrical appliance is closed via the contact areas. The insulation situated between the contact areas is intended to prevent inadvertent discharge of the cells. Thus, for example, many electrical appliances are fitted with a spiral spring as the electrical contact area, the jacket-type insulation protecting the two cell terminals against short-circuiting by inadvertent canting of said spiral spring. The insulating casing of the galvanic cells further protects the cells against environmental influences which lead to scratches, spots or traces of corrosion on the cell jar. The insulating casing of the galvanic cells is also provided with inscriptions and advertising material. On the one hand, this decor comprises information on the electrochemical system used, the cell size, the cell voltage, the manufacturer, the country of origin and the guarantee period, but it is also intended to provide, by the way it is designed, an appropriate advertising message.
German patents DE 1671802 and DE 2845242 disclose metallic casings for galvanic cells, which on their outside have a decorative layer. These metallic casings are primarily employed for galvanic cells of the Leclanche type, to prevent electrolyte from escaping after the cells have been completely discharged. In the case of galvanic cells of the Leclanche type it is possible, as complete discharge of the cells is approached, for holes to be formed in the zinc anode designed as the jar. To protect the cells of the above-mentioned type from leaking, they are provided, an insulating layer being interposed, with a metallic jacket which is provided with a decorative layer. The above-described jacketing technique is also employed in galvanic cells of the alkali-manganese type. To increase the capacity of the cells, the film labels or adhesive labels disclosed by the documents U.S. Pat. No. 4,869,978, PCT application WO 94/19835 and U.S. Pat. No. 4,801,514 have been used, for some time now, for the purpose of electrical insulation and as decor, since it is thus possible to reduce the thickness of the casing. Keeping the dimensions of the galvanic cell constant it is thereby possible to use a larger cell vessel and thus to introduce more active compound into the cells. The known methods for electrically insulating jacketing of galvanic cells constitute a significant cost factor, and the battery manufacturers are also interested in reducing the thickness of the insulating layer.